A typical side-gusset bag has two opposite front and back face panels, a first and a second side gusset panel that extend opposite one another in a longitudinal direction and that connect respective longitudinally extending side edges of the front and back face panels to one another, a reclosable fastener that has at least one reclosable fastener strip and is provided at the first side gusset panel and extends transversely of the bag only over a portion of the width of the face panels and enables the first side gusset panel to be folded out to form a reclosable spout. See U.S. Pat. No. 6,971,794, U.S. Pat. No. 8,182,4070, EP 2 032 454 and US 2011/0033133.
Usually, the side-gusset bag is formed from a plastic film, in particular a multi-layered laminated film that has a thermally weldable inner layer forming an inner surface of the side-gusset bag and an outer layer forming an outer surface of the side-gusset bag. Such a laminated film can carry an inner imprint that is done before laminating.
One of the two side gusset panels is provided with the reclosable fastener. When folded in, it fixes and closes the respective side gusset panel between the face panels. When opened and folded out, it forms a spout. When the side-gusset bag is filled, a transversely extending upper weld is provided above the reclosable fastener, which upper weld has first to be torn off, cut off or peeled open in certain sections at a corresponding upper section for the first opening.
The side-gusset bags known from the prior art have a reclosable fastener with a single reclosable fastener strip that can be interlocked with itself and that extends on the inside of the bag at a side gusset panel and, adjacent the gusset panel, it extends also on the front and back face panels and connects the side gusset panel with the front and back face panels. Thus, extending from a center line of the side gusset panel, a subpanel formed by one half of the side gusset panel is connected to the first face panel and the other half of the side gusset panel is connected to the second face panel.
According to the prior art, the length of the reclosable fastener strip on the front and back face panels can be different. In particular, the reclosable fastener strip on the face panels can also extend beyond the corresponding side gusset panel so that the front and back face panels are then directly connected to one another adjacent the side gusset panel, thereby providing a larger removal opening. However, the reclosable fastener always extends only over a portion of the entire transverse width of the face panels. Advantageously, a connection line, in particular a thermal weld, running either in the longitudinal direction or the transverse direction of the bag can also be provided adjacent the reclosable fastener strip in order to limit the opening.
Various methods of making side-gusset bags are known in practice. The prior-art side-gusset bags having a reclosable fastener at only one side gusset panel and the associated sections of the face panels are formed from a single film web by folding. The reclosable fastener strip that can be interlocked with itself is placed onto the flat-lying material web, and then one of the side gusset panels is formed at the reclosable fastener strip. From a side-gusset tube having face panels and gusset panel-forming side walls, individual side-gusset bags or corresponding blanks are then cut, each of them having a reclosable fastener strip.
Since the production direction of the material web or the side-gusset tube corresponds to the longitudinal direction of the side gusset panels, the corresponding methods are also designated as “longitudinal methods.”
Individual side-gusset bags are thus cut from the side gusset panel tube, and filling can take place immediately according to the so-called FFS (Form Fill and Seal) method. As an alternative, it is also possible to first make prefabricated side-gusset bags that are open at at least at one end and, for the time being, can be stored and delivered to a packaging site. Such side-gusset bags are then filled and sealed separately.
Also known from practice are alternative production methods in which the face panels and the side gusset panels are formed from separate film sections. For example, U.S. Pat. No. 7,331,191 describes a method of making film packaging bags in which a bag sheet is formed in such a manner that successive film packaging bags are arranged with their longitudinal bag edges positioned next to one another. Thus, the production direction extends transversely to the bags, which is why such a method is also designated as “transverse method” or as “Totani method.”
According to U.S. Pat. No. 7,331,191, first, a bag sheet of successive connected bag blanks is formed. A first film web is conveyed in the production direction. Subsequently, a film strip is fed in, and the edges of the film strip are folded over on a middle section. Usually, the edges have the same width so that a gap still remains after folding. Subsequently, pieces of the film strips are placed equally spaced apart from one another transverse to the production direction (thus, along the longitudinal bag direction) onto the first film web before a second film web is fed in the production direction so that the first film web and the pieces of the film strips are covered. Then, longitudinal welds are produced transverse to the production direction, so that on the one hand the film strips are welded to the second film web at the folded edges and on the other hand are welded to the first film web on an opposite side. The bag sheet formed in this way, finally, is cut into individual film packaging bags by cuts such that two side gusset panels of successive side-gusset bags are formed from a folded film strip. In addition to the side gusset panels, a separate bottom gusset panel as a flat bottom can also be produced.
With such a transverse method it is readily possible to make the side gusset panels shorter than the front and back face panels so that a continuous reclosable fastener that only connects the front and back face panels to one another can be provided above the side gusset panels. However, the provision of a reclosable fastener in region of one of the side gusset panel that allows folding out of the corresponding side gusset panel into a spout is not practical with the described transverse method because separate pieces of film are needed for forming the front and back face panels and the side gusset panels and subsequently have to be connected and then it is not possible to mount a reclosable fastener on one of the side gusset panels and the associated sections of the face panels with usual technical means.
In order to produce a bottom floor panel for the prior-art side-gusset bags having a reclosable fastener on a side gusset panel, a lower edge of the side-gusset bag can be closed with a transverse weld, and then, however, uniform placement of the side-gusset bag is not possible. Rather, such a side-gusset bag has a tendency to tilt to the side during filling, transportation or storage when the side-gusset is to be placed down with its lower section as the bottom.
In order to reduce this tendency to tilt over, it is known to first close a lower section of the side-gusset bag with a transverse weld and then fold it onto itself so that a kind of a reinforced double-wall bottom is formed. However, this approach is disadvantageous due to the fact that it requires an additional step for folding, and folding the lower section onto itself also results in increased material requirements. Finally, by folding the end section in one direction, a certain asymmetry remains so that an inclined position cannot be avoided completely. Also, producing additional corner welds or the like cannot entirely solve the described problem.